This invention relates to a hydroponic apparatus.
This invention has particular but not exclusive application to a hydroponic apparatus, and for illustrative purposes reference will be made to such application.
Hydroponics involves growing plants in the absence of soil, the necessary nutrients being delivered to the plants in the form of a nutrient solution in water, which passes over the roots of the plant. Hydroponic techniques have certain advantages over more conventional agriculture, which include the ability to carefully control optimum feeding, the elimination of weeds and it allows an improved control of pests and diseases. However, there is a high capital cost compared to traditional methods of agriculture. For this reason, hydroponic cultivation has to be carried out relatively intensively and efficiently if it is to be commercially viable.
One hydroponic method is where the roots of the plants are contained in gullies or conduits which are irrigated, generally continuously, with a nutrient solution.
Many designs for efficient, long lasting and easily installed gully or conduit systems have been trialed.
Various rigid and semi-rigid gullies and conduits are known.
For example, there are rigid plastic extruded conduits of rectangular or circular cross-section.
However, a number of disadvantages are evident with the existing rigid-type conduits. For example, with flat-based conduits, the nutrient flow is not always concentrated through the roots. Rather the flow of nutrients can pass either side of the roots, thus depriving the roots of maximum exposure to the nutrients. Furthermore, the flat top of such conduits tend to trap rain water which has a tendency which in turn may enter the conduit through the opening through which the plant is growing, thus diluting the nutrient solution.
With circular conduits, the roots of the plant are constrained such that, essentially, the lateral growth of the roots equals the longitudinal growth, whereas, in nature, it is preferred that the lateral growth be greater than the longitudinal growth. This can be obviated by transplanting the plant to a conduit having a larger internal diameter at an appropriate time in the development of the plant. However the additional handling of the plant increases costs of production. A further disadvantage of a circular conduit is that it is too xe2x80x9cdeepxe2x80x9d for certain plants such as lettuce and herbs which only have a shallow root ball and thus cannot be effectively coated with the nutrient solution.
It is also known to provide a completely flexible plastic tube which is not dimensionally stable. The tube need to be filled with a growing medium and the tube takes the shape of the growing medium. Typically, these flexible tubes adopt a somewhat elliptical shape due to sagging of the growing medium in the tube. However the tube is completely filled with the growing medium and this impedes water flow, air circulation and is quite unsatisfactory.
The present invention aims to alleviate at least one of the abovementioned disadvantages and to provide a hydroponic apparatus which will be reliable and efficient in use. Other objects and advantages of this invention will hereinafter become apparent.
Throughout this specification, the term xe2x80x9csubstantially elliptical cross-sectionxe2x80x9d is not limited to a cross-section which delineates a regular oval, but includes within its scope any related non-regular cross-section or similar but wherein the major axis remains of a greater length than the minor axis.
With the foregoing and other objects in view this invention relates to a hydroponic conduit comprising a dimensionally stable elongate member having at least one opening formed therein through which a plant may extend, wherein the elongate member is of substantially elliptical cross-section having an upper surface and a major axis, said at least one opening being formed in the upper surface of said member and wherein the major axis of the substantially elliptical cross-section of said member is substantially horizontal.
By being dimensionally stable, the hydroponic conduit can keep the desired elliptical cross-section without needing to be filled with a growing medium as is the case with an entirely flexible tube. Thus, the dimensionally stable elliptical conduit can be only partially filled with a growing medium that means that water circulation, air circulation and the like is improved.
Preferably, the elongated member includes a plurality of openings formed therein and wherein the spacing between adjacent openings may be determined by the type of plant to be grown. For example, the openings may be spaced at regular intervals longitudinally along one surface of the member and wherein each opening may be substantially co-axial with the minor axis of the member.
Because the elongated member may be initially provided to purchasers as a hollow elongated member without any openings formed therein, in one embodiment, an etched line may be provided along one surface of the member, such as a line co-axial with the minor axis of the member. The etch line may be used as a guide for the centre of openings to be cut into the member subsequently by the purchasers according to their individual requirements.
In use, the conduit would be used as a component of a hydroponic apparatus and in a method of hydroponic culture.
Therefore, according to a second aspect of the present invention, there is provided a hydroponic apparatus for use in hydroponic culture, said apparatus including:
at least one conduit comprising an elongated member of substantially elliptical cross-section, said conduit being provided with inlet means for introducing a nutrient solution into said conduit, outlet means for allowing the nutrient solution to exit said conduit and at least one opening formed therein through which a plant may extend.
In one embodiment there may be provided inlet means associated with each end of the conduit and outlet means associated with an intermediate portion of the conduit. In yet another embodiment the inlet means may be associated with a portion of the conduit intermediate the opposing ends of the conduit and wherein each end may include outlet means.
However, preferably the inlet means is associated with one end of the conduit and the outlet means is associated with the opposing end of the conduit.
The conduit is preferably of the type described above.
Furthermore, it will be appreciated that the apparatus may include a multiplicity of conduits positioned such that the major axes are substantially horizontal and in a side-by-side relationship. The conduits may be supported by a supporting structure such as a table.
The outlet means may include drainage means, such as a sump, which may be adapted to collect solid or semi-solid detritus and separate same from the exiting nutrient solution before the thus-depleted solution is returned to the inlet means of the conduit.
In yet another aspect of this invention, there is provided a method of hydroponic culture, said method including:
providing a hydroponic conduit comprising an elongated member of substantially elliptical cross-section, said conduit being provided with inlet means for introducing a nutrient solution into said conduit, outlet means for allowing the nutrient solution to exit said conduit and at least one opening formed therein through which a plant may extend;
supporting a seedling within said opening such that at least some of the roots of the seedling are retained within the conduit; and
using the inlet means to introduce a sufficient quantity of a nutrient solution into said conduit to make contact with the roots of the seedling.